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Table of Common Z-Transforms

Module by: Melissa Selik, Richard Baraniuk. E-mail the authors

Summary: Lists the z-transfrom and the ROC for several generalized, common signals.

Note: You are viewing an old version of this document. The latest version is available here.

The table below will focus on unilateral and bilateral z-transforms. When given a signal (or sequence), the table can be very useful in finding the corresponding z-transform. The table also specifies the region of convergence, which allows us to pick out the unilateral and bilateral transforms.


The notation for z z found in the table below may differ from that found in other tables. For example, the basic z-transform of un u n can be written as either of the following two expressions, which are equal:
zz1=11z-1 z z 1 1 1 z -1

Table 1
Signal Z-Transform ROC
δnk δ n k zk z k Allz All z
un u n zz1 z z 1 |z|>1 z 1
u(n)1 u n 1 zz1 z z 1 |z|<1 z 1
nun n u n zz12 z z 1 2 |z|>1 z 1
n2un n 2 u n z(z+1)z13 z z 1 z 1 3 |z|>1 z 1
n3un n 3 u n z(z2+4z+1)z14 z z 2 4 z 1 z 1 4 |z|>1 z 1
(αn)u(n)1 α n u n 1 zzα z z α |z|<|α| z α
αnun α n u n zzα z z α |z|>|α| z α
nαnun n α n u n αzzα2 α z z α 2 |z|>|α| z α
n2αnun n 2 α n u n αz(z+α)zα3 α z z α z α 3 |z|>|α| z α
k =1mnk+1αmm!αnun k 1 m n k 1 α m m α n u n zzαm+1 z z α m 1
γncosαnun γ n α n u n z(zγcosα)z2(2γcosα)z+γ2 z z γ α z 2 2 γ α z γ 2 |z|>|α| z α
γnsinαnun γ n α n u n zγsinαz2(2γcosα)z+γ2 z γ α z 2 2 γ α z γ 2 |z|>|α| z α

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